Hybrid risers systems used in recent offshore oil & gas projects to decouple large platform motions from main body of the risers can only support a single riser or a small number of risers. In the Sapinhoa Lula NE FPSO project, the challenge was how to design a riser system comprised of over forty risers and umbilical for each of the two FPSOs in 2,200 meter of deep water. The solution is large submerged Buoys with a unique hull form, each of them capable of supporting twenty plus risers and umbilical. The system is called Buoy Supported Riser system, or BSR system.
Comprehensive analyses have been performed during the design of the BSR system. In-depth study of the BRS’ hydrodynamic behavior has been performed to ensure that it meets all design requirements for a 30 year operation life and can be installed safely. Model tests including VIM tests have been conducted to verify hydrodynamic coefficients for the in-place and installation conditions.
The main objective of this paper is to present the hydrodynamic analysis methodology for the design of BSR system.